Much has been said in the past with regard to Donald Trump and his relationship with North Korean leader Kim Jong Un. They started off as Twitter enemies, then reached a certain friendship where they are at the point of sending letters to each other.

But what is surprising to many at this point is that Trump is even taking the side of Kim over that of his own CIA after a story that Kim's half-brotherworked for the agency before he was killed in 2017, and the president said he never would have allowed the CIA to work with him.

Kim Jong Nam was at one time the recognized rightful heir to the North Korean dynasty, yet became an outcast in the Kim family.

In February 2017 an Indonesian woman and a Vietnamese woman smeared a nerve agent on Kim's face at the Kuala Lumpur International Airport, killing him. Attorneys for the accused women argued that they didn't know what they were doing and thought they were participating in a prank for a TV show.

The Wall Street Journal claimed in an article Monday that the elder Kim son had been a CIA source and had met with operatives for the agency on multiple occasions.

These claims are in a book about the younger Kim brother, Kim Jong Un, that was written by Washington Post reporter Anna Fitfield. "The Great Successor" was published on Tuesday.

Trump, who took office just a few weeks before Kim Jong Nam's death, said repeatedly after the reports of the connection between the late North Korean and the CIA that he didn't know where it was true or not.

He also indicated, "I know this, that the relationship is such that that wouldn't happen under my auspices, but I don't know about that. Nobody knows."

The president also said that he'd "just received a beautiful letter from Kim Jong Un" and that he believes the relationship he shares with him is "very well," noting that he appreciated the letter.

Things have been tense between Trump and Kim after a failed summit earlier this year. Trump left early when the talks seemed to go south. Yet, Trump also insisted on Tuesday that Kim had so far "kept his word" with regard to not holding any nuclear and missile testing.

Before Trump spoke up, however, National Security Adviser John Bolton said Kim wasn't obeying the terms of the agreement from last year's summit in Singapore.

"They're doing a lot of other things that still indicate that they have not made a strategic decision to give up the pursuit of deliverable weapons, which is why we continue the maximum pressure campaign," he added.